On the structure, morphology and electrical conductivities of titanium oxide thin films

Titanium oxide thin films were prepared by a d.c. sputtering technique onto glass substrates. The morphology of the films was analysed by atomic force microscopy and their structure by X-ray diffraction. The structure and phase composition of the films depend on the deposition conditions. The small values for roughness obtained from AFM, ranging from 3 to 9 nm, show relatively smooth surfaces. Temperature dependences of the electrical conductivities were studied in a wide range, 13–560 K. The values of activation energies of electrical conduction, calculated from the temperature dependences of the electrical conductivity, varied between 0.13 and 0.39 eV, for temperature range 310–468 K. The current–voltage characteristics are ohmic for values of applied voltage lower than 0.5 V. For higher values, the mechanism of electrical conduction is determined by space-charge-limited currents.